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1 | /* |
2 | * xt_HMARK - Netfilter module to set mark by means of hashing |
3 | * |
4 | * (C) 2012 by Hans Schillstrom <hans.schillstrom@ericsson.com> |
5 | * (C) 2012 by Pablo Neira Ayuso <pablo@netfilter.org> |
6 | * |
7 | * This program is free software; you can redistribute it and/or modify it |
8 | * under the terms of the GNU General Public License version 2 as published by |
9 | * the Free Software Foundation. |
10 | */ |
11 | |
12 | #include <linux/module.h> |
13 | #include <linux/skbuff.h> |
14 | #include <linux/icmp.h> |
15 | |
16 | #include <linux/netfilter/x_tables.h> |
17 | #include <linux/netfilter/xt_HMARK.h> |
18 | |
19 | #include <net/ip.h> |
20 | #if IS_ENABLED(CONFIG_NF_CONNTRACK) |
21 | #include <net/netfilter/nf_conntrack.h> |
22 | #endif |
23 | #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES) |
24 | #include <net/ipv6.h> |
25 | #include <linux/netfilter_ipv6/ip6_tables.h> |
26 | #endif |
27 | |
28 | MODULE_LICENSE("GPL"); |
29 | MODULE_AUTHOR("Hans Schillstrom <hans.schillstrom@ericsson.com>"); |
30 | MODULE_DESCRIPTION("Xtables: packet marking using hash calculation"); |
31 | MODULE_ALIAS("ipt_HMARK"); |
32 | MODULE_ALIAS("ip6t_HMARK"); |
33 | |
34 | struct hmark_tuple { |
35 | __be32 src; |
36 | __be32 dst; |
37 | union hmark_ports uports; |
38 | u8 proto; |
39 | }; |
40 | |
41 | static inline __be32 hmark_addr6_mask(const __be32 *addr32, const __be32 *mask) |
42 | { |
43 | return (addr32[0] & mask[0]) ^ |
44 | (addr32[1] & mask[1]) ^ |
45 | (addr32[2] & mask[2]) ^ |
46 | (addr32[3] & mask[3]); |
47 | } |
48 | |
49 | static inline __be32 |
50 | hmark_addr_mask(int l3num, const __be32 *addr32, const __be32 *mask) |
51 | { |
52 | switch (l3num) { |
53 | case AF_INET: |
54 | return *addr32 & *mask; |
55 | case AF_INET6: |
56 | return hmark_addr6_mask(addr32, mask); |
57 | } |
58 | return 0; |
59 | } |
60 | |
61 | static inline void hmark_swap_ports(union hmark_ports *uports, |
62 | const struct xt_hmark_info *info) |
63 | { |
64 | union hmark_ports hp; |
65 | u16 src, dst; |
66 | |
67 | hp.b32 = (uports->b32 & info->port_mask.b32) | info->port_set.b32; |
68 | src = ntohs(hp.b16.src); |
69 | dst = ntohs(hp.b16.dst); |
70 | |
71 | if (dst > src) |
72 | uports->v32 = (dst << 16) | src; |
73 | else |
74 | uports->v32 = (src << 16) | dst; |
75 | } |
76 | |
77 | static int |
78 | hmark_ct_set_htuple(const struct sk_buff *skb, struct hmark_tuple *t, |
79 | const struct xt_hmark_info *info) |
80 | { |
81 | #if IS_ENABLED(CONFIG_NF_CONNTRACK) |
82 | enum ip_conntrack_info ctinfo; |
83 | struct nf_conn *ct = nf_ct_get(skb, &ctinfo); |
84 | struct nf_conntrack_tuple *otuple; |
85 | struct nf_conntrack_tuple *rtuple; |
86 | |
87 | if (ct == NULL || nf_ct_is_untracked(ct)) |
88 | return -1; |
89 | |
90 | otuple = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple; |
91 | rtuple = &ct->tuplehash[IP_CT_DIR_REPLY].tuple; |
92 | |
93 | t->src = hmark_addr_mask(otuple->src.l3num, otuple->src.u3.ip6, |
94 | info->src_mask.ip6); |
95 | t->dst = hmark_addr_mask(otuple->src.l3num, rtuple->src.u3.ip6, |
96 | info->dst_mask.ip6); |
97 | |
98 | if (info->flags & XT_HMARK_FLAG(XT_HMARK_METHOD_L3)) |
99 | return 0; |
100 | |
101 | t->proto = nf_ct_protonum(ct); |
102 | if (t->proto != IPPROTO_ICMP) { |
103 | t->uports.b16.src = otuple->src.u.all; |
104 | t->uports.b16.dst = rtuple->src.u.all; |
105 | hmark_swap_ports(&t->uports, info); |
106 | } |
107 | |
108 | return 0; |
109 | #else |
110 | return -1; |
111 | #endif |
112 | } |
113 | |
114 | /* This hash function is endian independent, to ensure consistent hashing if |
115 | * the cluster is composed of big and little endian systems. */ |
116 | static inline u32 |
117 | hmark_hash(struct hmark_tuple *t, const struct xt_hmark_info *info) |
118 | { |
119 | u32 hash; |
120 | u32 src = ntohl(t->src); |
121 | u32 dst = ntohl(t->dst); |
122 | |
123 | if (dst < src) |
124 | swap(src, dst); |
125 | |
126 | hash = jhash_3words(src, dst, t->uports.v32, info->hashrnd); |
127 | hash = hash ^ (t->proto & info->proto_mask); |
128 | |
129 | return (((u64)hash * info->hmodulus) >> 32) + info->hoffset; |
130 | } |
131 | |
132 | static void |
133 | hmark_set_tuple_ports(const struct sk_buff *skb, unsigned int nhoff, |
134 | struct hmark_tuple *t, const struct xt_hmark_info *info) |
135 | { |
136 | int protoff; |
137 | |
138 | protoff = proto_ports_offset(t->proto); |
139 | if (protoff < 0) |
140 | return; |
141 | |
142 | nhoff += protoff; |
143 | if (skb_copy_bits(skb, nhoff, &t->uports, sizeof(t->uports)) < 0) |
144 | return; |
145 | |
146 | hmark_swap_ports(&t->uports, info); |
147 | } |
148 | |
149 | #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES) |
150 | static int get_inner6_hdr(const struct sk_buff *skb, int *offset) |
151 | { |
152 | struct icmp6hdr *icmp6h, _ih6; |
153 | |
154 | icmp6h = skb_header_pointer(skb, *offset, sizeof(_ih6), &_ih6); |
155 | if (icmp6h == NULL) |
156 | return 0; |
157 | |
158 | if (icmp6h->icmp6_type && icmp6h->icmp6_type < 128) { |
159 | *offset += sizeof(struct icmp6hdr); |
160 | return 1; |
161 | } |
162 | return 0; |
163 | } |
164 | |
165 | static int |
166 | hmark_pkt_set_htuple_ipv6(const struct sk_buff *skb, struct hmark_tuple *t, |
167 | const struct xt_hmark_info *info) |
168 | { |
169 | struct ipv6hdr *ip6, _ip6; |
170 | int flag = IP6_FH_F_AUTH; |
171 | unsigned int nhoff = 0; |
172 | u16 fragoff = 0; |
173 | int nexthdr; |
174 | |
175 | ip6 = (struct ipv6hdr *) (skb->data + skb_network_offset(skb)); |
176 | nexthdr = ipv6_find_hdr(skb, &nhoff, -1, &fragoff, &flag); |
177 | if (nexthdr < 0) |
178 | return 0; |
179 | /* No need to check for icmp errors on fragments */ |
180 | if ((flag & IP6_FH_F_FRAG) || (nexthdr != IPPROTO_ICMPV6)) |
181 | goto noicmp; |
182 | /* Use inner header in case of ICMP errors */ |
183 | if (get_inner6_hdr(skb, &nhoff)) { |
184 | ip6 = skb_header_pointer(skb, nhoff, sizeof(_ip6), &_ip6); |
185 | if (ip6 == NULL) |
186 | return -1; |
187 | /* If AH present, use SPI like in ESP. */ |
188 | flag = IP6_FH_F_AUTH; |
189 | nexthdr = ipv6_find_hdr(skb, &nhoff, -1, &fragoff, &flag); |
190 | if (nexthdr < 0) |
191 | return -1; |
192 | } |
193 | noicmp: |
194 | t->src = hmark_addr6_mask(ip6->saddr.s6_addr32, info->src_mask.ip6); |
195 | t->dst = hmark_addr6_mask(ip6->daddr.s6_addr32, info->dst_mask.ip6); |
196 | |
197 | if (info->flags & XT_HMARK_FLAG(XT_HMARK_METHOD_L3)) |
198 | return 0; |
199 | |
200 | t->proto = nexthdr; |
201 | if (t->proto == IPPROTO_ICMPV6) |
202 | return 0; |
203 | |
204 | if (flag & IP6_FH_F_FRAG) |
205 | return 0; |
206 | |
207 | hmark_set_tuple_ports(skb, nhoff, t, info); |
208 | return 0; |
209 | } |
210 | |
211 | static unsigned int |
212 | hmark_tg_v6(struct sk_buff *skb, const struct xt_action_param *par) |
213 | { |
214 | const struct xt_hmark_info *info = par->targinfo; |
215 | struct hmark_tuple t; |
216 | |
217 | memset(&t, 0, sizeof(struct hmark_tuple)); |
218 | |
219 | if (info->flags & XT_HMARK_FLAG(XT_HMARK_CT)) { |
220 | if (hmark_ct_set_htuple(skb, &t, info) < 0) |
221 | return XT_CONTINUE; |
222 | } else { |
223 | if (hmark_pkt_set_htuple_ipv6(skb, &t, info) < 0) |
224 | return XT_CONTINUE; |
225 | } |
226 | |
227 | skb->mark = hmark_hash(&t, info); |
228 | return XT_CONTINUE; |
229 | } |
230 | #endif |
231 | |
232 | static int get_inner_hdr(const struct sk_buff *skb, int iphsz, int *nhoff) |
233 | { |
234 | const struct icmphdr *icmph; |
235 | struct icmphdr _ih; |
236 | |
237 | /* Not enough header? */ |
238 | icmph = skb_header_pointer(skb, *nhoff + iphsz, sizeof(_ih), &_ih); |
239 | if (icmph == NULL || icmph->type > NR_ICMP_TYPES) |
240 | return 0; |
241 | |
242 | /* Error message? */ |
243 | if (icmph->type != ICMP_DEST_UNREACH && |
244 | icmph->type != ICMP_SOURCE_QUENCH && |
245 | icmph->type != ICMP_TIME_EXCEEDED && |
246 | icmph->type != ICMP_PARAMETERPROB && |
247 | icmph->type != ICMP_REDIRECT) |
248 | return 0; |
249 | |
250 | *nhoff += iphsz + sizeof(_ih); |
251 | return 1; |
252 | } |
253 | |
254 | static int |
255 | hmark_pkt_set_htuple_ipv4(const struct sk_buff *skb, struct hmark_tuple *t, |
256 | const struct xt_hmark_info *info) |
257 | { |
258 | struct iphdr *ip, _ip; |
259 | int nhoff = skb_network_offset(skb); |
260 | |
261 | ip = (struct iphdr *) (skb->data + nhoff); |
262 | if (ip->protocol == IPPROTO_ICMP) { |
263 | /* Use inner header in case of ICMP errors */ |
264 | if (get_inner_hdr(skb, ip->ihl * 4, &nhoff)) { |
265 | ip = skb_header_pointer(skb, nhoff, sizeof(_ip), &_ip); |
266 | if (ip == NULL) |
267 | return -1; |
268 | } |
269 | } |
270 | |
271 | t->src = ip->saddr & info->src_mask.ip; |
272 | t->dst = ip->daddr & info->dst_mask.ip; |
273 | |
274 | if (info->flags & XT_HMARK_FLAG(XT_HMARK_METHOD_L3)) |
275 | return 0; |
276 | |
277 | t->proto = ip->protocol; |
278 | |
279 | /* ICMP has no ports, skip */ |
280 | if (t->proto == IPPROTO_ICMP) |
281 | return 0; |
282 | |
283 | /* follow-up fragments don't contain ports, skip all fragments */ |
284 | if (ip->frag_off & htons(IP_MF | IP_OFFSET)) |
285 | return 0; |
286 | |
287 | hmark_set_tuple_ports(skb, (ip->ihl * 4) + nhoff, t, info); |
288 | |
289 | return 0; |
290 | } |
291 | |
292 | static unsigned int |
293 | hmark_tg_v4(struct sk_buff *skb, const struct xt_action_param *par) |
294 | { |
295 | const struct xt_hmark_info *info = par->targinfo; |
296 | struct hmark_tuple t; |
297 | |
298 | memset(&t, 0, sizeof(struct hmark_tuple)); |
299 | |
300 | if (info->flags & XT_HMARK_FLAG(XT_HMARK_CT)) { |
301 | if (hmark_ct_set_htuple(skb, &t, info) < 0) |
302 | return XT_CONTINUE; |
303 | } else { |
304 | if (hmark_pkt_set_htuple_ipv4(skb, &t, info) < 0) |
305 | return XT_CONTINUE; |
306 | } |
307 | |
308 | skb->mark = hmark_hash(&t, info); |
309 | return XT_CONTINUE; |
310 | } |
311 | |
312 | static int hmark_tg_check(const struct xt_tgchk_param *par) |
313 | { |
314 | const struct xt_hmark_info *info = par->targinfo; |
315 | |
316 | if (!info->hmodulus) { |
317 | pr_info("xt_HMARK: hash modulus can't be zero\n"); |
318 | return -EINVAL; |
319 | } |
320 | if (info->proto_mask && |
321 | (info->flags & XT_HMARK_FLAG(XT_HMARK_METHOD_L3))) { |
322 | pr_info("xt_HMARK: proto mask must be zero with L3 mode\n"); |
323 | return -EINVAL; |
324 | } |
325 | if (info->flags & XT_HMARK_FLAG(XT_HMARK_SPI_MASK) && |
326 | (info->flags & (XT_HMARK_FLAG(XT_HMARK_SPORT_MASK) | |
327 | XT_HMARK_FLAG(XT_HMARK_DPORT_MASK)))) { |
328 | pr_info("xt_HMARK: spi-mask and port-mask can't be combined\n"); |
329 | return -EINVAL; |
330 | } |
331 | if (info->flags & XT_HMARK_FLAG(XT_HMARK_SPI) && |
332 | (info->flags & (XT_HMARK_FLAG(XT_HMARK_SPORT) | |
333 | XT_HMARK_FLAG(XT_HMARK_DPORT)))) { |
334 | pr_info("xt_HMARK: spi-set and port-set can't be combined\n"); |
335 | return -EINVAL; |
336 | } |
337 | return 0; |
338 | } |
339 | |
340 | static struct xt_target hmark_tg_reg[] __read_mostly = { |
341 | { |
342 | .name = "HMARK", |
343 | .family = NFPROTO_IPV4, |
344 | .target = hmark_tg_v4, |
345 | .targetsize = sizeof(struct xt_hmark_info), |
346 | .checkentry = hmark_tg_check, |
347 | .me = THIS_MODULE, |
348 | }, |
349 | #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES) |
350 | { |
351 | .name = "HMARK", |
352 | .family = NFPROTO_IPV6, |
353 | .target = hmark_tg_v6, |
354 | .targetsize = sizeof(struct xt_hmark_info), |
355 | .checkentry = hmark_tg_check, |
356 | .me = THIS_MODULE, |
357 | }, |
358 | #endif |
359 | }; |
360 | |
361 | static int __init hmark_tg_init(void) |
362 | { |
363 | return xt_register_targets(hmark_tg_reg, ARRAY_SIZE(hmark_tg_reg)); |
364 | } |
365 | |
366 | static void __exit hmark_tg_exit(void) |
367 | { |
368 | xt_unregister_targets(hmark_tg_reg, ARRAY_SIZE(hmark_tg_reg)); |
369 | } |
370 | |
371 | module_init(hmark_tg_init); |
372 | module_exit(hmark_tg_exit); |
373 |
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